Coxiella burnetii causing haemophagocytic syndrome: a rare complication of an unusual pathogen.

We describe an unusual presentation of Q fever with associated haemophagocytic syndrome, confirmed by bone marrow aspirate, Q fever polymerase chain reaction (PCR) and serological testing. Clinical recovery was observed after the commencement of doxycycline with normalisation of the patient's full blood count and serum biochemistry. Serial monitoring of the Q fever serology revealed the subsequent development of sustained high phase 1 IgG antibodies, suggestive of chronic Q fever. Although many infectious aetiologies have been associated with haemophagocytosis, Q fever has only rarely been described in this context. The diagnosis of Q fever is often overlooked, especially when the presentation is atypical. We describe how the use of PCR testing significantly shortened the interval to definitive diagnosis and helped elucidate the underlying cause of the patient's haematological disorder.